FILE - In this Dec. 9, 2005 file photo, French citizen Florence Cassez is shown to the press during a police reenactment for the media of her arrest, a day after her detainment, on the outskirts of Mexico City. A Mexican Supreme Court panel voted Wednesday, Jan. 23, 2013, to release Cassez, who was sentenced to 60 years in prison for kidnapping. Cassez was arrested in 2005 and convicted of helping her Mexican then-boyfriend run a kidnap gang. The five-justice panel voted 3-2 to order Cassez released because of procedural and rights violations during her arrest. (AP Photo, File) (The Associated Press)

Bernard Cassez, father of imprisoned French citizen Florence Cassez, exits the jail after visiting her in Mexico City, Tuesday, Jan. 22, 2013. Cassez is serving a 60-year sentence in Mexico for kidnapping three people. (AP Photo/Andres Leighton) (The Associated Press)

Agustin Acosta, left, lawyer of the imprisoned Frenchwoman Florence Cassez, is congratulated by an unidentified person in Mexico City, Wednesday, Jan. 23, 2013. The Mexican Supreme Court panel voted Wednesday to release Florence Cassez, who was sentenced to 60 years in prison for kidnapping. Cassez was arrested in 2005 and convicted of helping her Mexican then-boyfriend run a kidnap gang. The five-justice panel voted 3-2 to order Cassez released because of procedural and rights violations during her arrest. (AP Photo/Eduardo Verdugo) (The Associated Press)

Supreme Court Justice ministers hold a panel hearing reviewing the case of French woman Florence Cassez in Mexico City, Wednesday, Jan. 23, 2013. The Mexican Supreme Court panel voted Wednesday to release Cassez, who was sentenced to 60 years in prison for kidnapping. Cassez was arrested in 2005 and convicted of helping her Mexican then-boyfriend run a kidnap gang. The five-justice panel voted 3-2 to order Cassez released because of procedural and rights violations during her arrest. (AP Photo/Eduardo Verdugo) (The Associated Press)

Supreme Court Justice Minister, Arturo Zaldivar, attends a panel hearing in Mexico City, Wednesday, Jan. 23, 2013. The Mexican Supreme Court panel voted Wednesday to release Florence Cassez, a Frenchwoman who was sentenced to 60 years in prison for kidnapping. Cassez was arrested in 2005 and convicted of helping her Mexican then-boyfriend run a kidnap gang. The five-justice panel voted 3-2 to order Cassez released because of procedural and rights violations during her arrest. (AP Photo/Eduardo Verdugo) (The Associated Press)

MEXICO CITY – A Frenchwoman who became a cause celebre in her homeland after she was sentenced to 60 years in a Mexican prison for kidnapping left on a late-night flight for Paris Wednesday following a Supreme Court ruling that her trial was tainted and she must be freed.

Florence Cassez's arrest, trial and seven years of imprisonment in Mexico had strained relations between the countries and led consecutive French presidents to call for her release. Anti-crime activists in Mexico have bitterly objected to efforts to release the 38-year-old.

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Cassez's flight left Mexico City's international airport at 9:25 p.m. local time (03:25 GMT) and was expected to arrive in Paris about 10 hours later.

Relatives of kidnap victims angrily shouted "Killer!" as a police convoy with sirens flashing escorted a sports utility vehicle out of the Mexico City prison where Cassez had been held. Social media sites in Mexico boiled with indignation, both at her release and the sad state of Mexico's legal and police systems.

Supporters of Cassez, who was arrested in 2005 and convicted of helping her Mexican then-boyfriend run a kidnap gang, celebrated the decision, saying she was innocent.

"I'm crazy with happiness, I can't say anything else," her mother, Charlotte Cassez, said in France. "I'm still struggling to believe it."

Earlier Wednesday, a Mexican Supreme Court panel voted 3-2 to release Cassez because of procedural and rights violations during her arrest, including police staging a recreation of her capture for the media. The justices pointedly did not rule on her guilt or innocence, but said the violations of due process, the right to consular assistance and evidentiary rules were so grievous that they invalidated the original guilty verdict against her.

One justice originally proposed on Wednesday asking an appeals court to review her trial, omitting the tainted evidence; however, most of the justices on the panel indicated they would oppose that, and they then voted to simply release her.

Wednesday's ruling put yet another spotlight on Mexico's historically corrupt and broken justice system and brought reactions from the highest levels of power.

"I want to recognize the Mexican justice system because it put the law first," French President Francois Hollande said on television. "That was the trust we put in it. And today we can say that between France and Mexico, we have the best relations that it is possible to have."

Mexican President Enrique Pena Nieto said in a statement that he will "absolutely" respect the court's decision.

"This is a resounding message in favor of justice and respect for human rights," Agustin Acosta, an attorney for Cassez, said outside the courtroom. Police torture and fabrication of evidence have long been tolerated in Mexico.

Mexican police acknowledged that they later staged a televised raid on a ranch outside Mexico City to depict the rescue of the hostages and detention of Cassez. After Cassez was detained and held incognito for a day, Mexican police hauled her back to the ranch and forced her to participate in their staging of the raid for television cameras, a sort of media display that is not unusual in Mexico.

The Frenchwoman said she had lived at the ranch, but did not know that kidnapping victims were being held there.

"If she had been turned over to court custody promptly, if she had been allowed prompt consular assistance, this (raid) staging couldn't have taken place, and the whole affair would have been totally different," Justice Arturo Zaldivar said during the discussion of the ruling.

The doe-eyed Cassez became the center of a vigorous debate between Mexicans who say she was abused by the criminal justice system and those who say setting her free would only reinforce a sense that crimes such as kidnapping go unpunished.

As reporters gathered outside the Mexico City prison where Cassez is being held, the wife of one of the kidnap victims showed up, sobbing.

Michelle Valadez, 34, said her husband Ignacio was kidnapped and held for three months by Cassez's boyfriend's gang in 2005.

"We paid the ransom, but they killed him anyway," she sobbed. "It's not fair what they've done to us, it's not fair they're freeing her." The issue is sensitive in Mexico, which has one of the highest kidnapping rates in the world and where there is increasing public pressure to halt what is seen as widespread impunity for criminals.

At least one victim identified Cassez as one of the kidnappers, though only by hearing her voice, not by seeing her.

"In this country we can no longer ignore police obtaining evidence by tampering with it, by using torture, by staging raids," said Luis Gonzalez Placencia, president of Mexico City's Human Rights Commission. "We will never know whether Florence is guilty or innocent, but we know for certain there are specific people who violated due process."

It was not immediately clear how the ruling might affect the case against Cassez's ex-boyfriend Israel Vallarta, who was arrested for allegedly leading the gang and is being tried separately.

Anti-crime activist Isabel Miranda de Wallace, who led a successful decade-long fight to bring her son's kidnappers to justice even though his body was never found, lashed out at the court's ruling.

"Today, they opened the door to impunity, today a lot of people are going to go free," Miranda de Wallace told local media. "We already live without public safety, now it's going to be worse."

Ezequiel Elizalde, a kidnap victim who testified against Cassez, told local media the Mexican justice system was discredited by the ruling, and that citizens should no longer depend on it. "Get a weapon, arm yourself, and don't pay any attention to the government."

Cassez was originally sentenced in 2008 to 96 years in prison for four kidnappings. The sentence was reduced to 70 years a year later when she was acquitted of one of the charges.

The case caused diplomatic tensions between France and Mexico. In 2011, the Mexican government said it would not participate in France's yearlong festival celebrating Mexican culture, after then-French President Nicolas Sarkozy said the festival should be used to draw attention to the Cassez case.

The case showed Mexico's legal system to be plagued by irregularities and a slow process.

Mexico in 2008 implemented a judicial reform that called for open trials and reinforced the principle of innocence until proven guilty. The old system, still in place in most of the country, was blamed for fostering corruption and confessions extracted by torture.

The country's Supreme Court has grown more independent in recent years, and the public has become more willing to acknowledge the shortcomings of the justice system. A widely viewed documentary film, "Presumed Guilty," detailed the story of a man arrested off the street and held for several years for a murder he didn't commit.